Catalytic cracking catalysts

ABSTRACT

Catalytic cracking catalysts and catalytic cracking process wherein the cracking catalysts are prepared by: (1) contacting a mixture of a large pore zeolite and an inorganic oxide matrix at effective conditions of temperature, pH and time with a fluoro salt; and (2) ammonium exchanging the product of step (1) to provide a catalyst having less than 0.3 percent by weight Na 2  O. Optionally, the product is provided with an effective amount of at least one cation selected from the class consisting of cerium, lanthanum, praseodymium, neodymium, promethium, samarium, europium, lutetium, gadolinium, terbium, dysprosium, holmium, erbium, thulium and ytterbium.

FIELD OF THE INVENTION

The present invention relates to new catalytic cracking catalysts, theirmethod of manufacture and to cracking processes employing suchcatalysts. The cracking catalysts comprise an inorganic oxide matrix anda large pore zeolite (6 Å to 15 Å) and are formed by a process thatachieves a low concentration of sodium ions in the final catalystwithout the requirement of energy intensive calcination steps heretoforeemployed for Na₂ O removal.

BACKGROUND OF THE INVENTION

The prior art dealing with catalytic cracking catalysts is voluminouswith a basic underlying goal being the preparation of modified zeolitesfor use as cracking catalysts. These zeolites are then added to alumina,silica, etc. as a matrix for the zeolite. The zeolitic component hasgenerally been zeolite Y and has essentially been unchanged for over adecade. The development of the art of cracking catalysts has centered,for the most part, on preparing catalyst formulations by employingpretreated zeolites which are then subsequently admixed with variousmatrices. Representative of such developments are those disclosed inU.S. Pat. Nos. 3,140,249, 3,352,796, 3,312,615 and 3,542,670.

Another approach has been related to various secondary treatments forzeolites, such as processes to lower the alkali metal content of thebasic zeolitic component (e.g., U.S. Pat. Nos. 3,293,192 and Re. 28,629)and processes to extrac aluminum from the zeolitic framework (to enhancethe thermal stability of the zeolite). Of course the latter processesnecessarily result in products having sites where aluminum has beenremoved, and accordingly, the zeolites formed by such a process have acertain instability as a result.

In EPC Application No. 81110620.3, having EPC Publication No. 82.211 andpublished June 29, 1983, incorporated herein by reference thereto, a newclass of zeolites is disclosed and denominated therein as zeolite"LZ-210". This class of aluminosilicates comprises aluminosilicateshaving a chemical composition expressed in terms of mole ratios ofoxides as:

    (0.85-1.1)M.sub.2/n O:Al.sub.2 O.sub.3 :xSiO.sub.2

wherein "M" is a cation having the valence "n", and "x" has a valuegreater then 6.0. LZ-210 is a new class of aluminosilicates having afaujasite structure and having an SiO₂ to Al₂ O₃ ratio greater than 6.0while not having the problems necessarily associated with dealuminated,i.e., aluminum extracted, zeolites.

Among the various prior art processes are processes involving thetreatment of zeolites with halogen-containing compounds whereby residualfluoride is provided to the zeolite. Representative of patents for suchprocesses are U.S. Pat. Nos. 3,620,960 (molybdenum fluoride); 3,630,965(hydrofluoric acid); 3,644,220 (volatile halides selected from the groupconsisting of aluminum, zirconium, titanium, tin, molybdenum, tungsten,chromium, vanadium, antimony, bismuth, iron, platinum group metals andrare earths); 3,575,887 (fluorides and chlorides); 3,699,056(halogenated hydrocarbons) 3,702,312 (fluorides and chlorides);4,427,788 (ammoniacal aluminum fluoride solution for treatment ofzeolites having a silica-to-alumina ratio greater than 100); and4,427,790 (complex fluoranion treatment of zeolites having asilica-to-alumina ratio greater than 100).

U.S. Pat. No. 4,427,790 is a recent patent disclosing that certainfluoroanions provide enhancement in the activity of crystalline zeoliteonly when the zeolites have silica-to-alumina ratios greater than about100. The patent also discloses the post-admixture of the treatedproducts with matrix materials. Interestingly, the patent inherentlyteaches that the process is beneficial only for the treatment of suchhigh silica zeolites and only when such zeolites are treated in theabsence of any other component.

One variation of the above fluoride treatments for zeolites is disclosedin U.S. Pat. No. 3,619,412. The process of U.S. Pat. No. 3,619,412comprises the treatment of a mixture of mordenite and amorphoussilica-alumina eith a solution of a fluorine compound such as ammoniumdifluoride or hydrofluoric acid. The hydrofluoric acid treatment is saidto provide stability to the treated catalyst. Further, processesinvolving specific treatments of zeolites having silica-to-aluminaratios greater than 100 are disclosed in U.S. Pat. Nos. 4,427,786;4,427,787; 4,427,789 and 4,427,791. U.S. Pat. No. 4,427,786 disclosesthe treatment of supported zeolites, wherein the zeolite has asilica-to-alumina ratio greater than 100, with boron fluoride,hydrolyzing of the boron fluoride, an ammonium salt exchange andcalcination. A comparison of examples 2 and 9 therein shows that theactivity of zeolites having a silica-to-alumina ratio of less than 70showed a decrease in activity as a result of the process. U.S. Pat. No.4,427,787 discloses the treatment on an alumina-supported zeolite, saidzeolite having a silica-to-alumina ratio greater than 100, with a diluteaqueous solution of hydrogen fluoride. The hydrogen fluoride treatmentis said to preferentially increase the activity of zeolites havingsilica-to-alumina ratios over 100. U.S. Pat. No. 4,427,789 discloses thetreatment of an alumina-supported zeolite, said zeolite having asilica-to-alumina ratio greater than 100, with an aqueous solution of analkali metal fluoride, impregnation with a warm solution of an ammoniumsalt and a calcination. U.S. Pat. No. 4,427,791 discloses a process forthe treatment of an inorganic oxide material with ammonium fluoride orboron trifluoride, ammonium exchange, and calcination. The treatment issaid to enhance the activity of the inorganic oxide material as a resultof the ammonium exchange step.

The use of LZ-210 and forms of LZ-210 as catalysts is disclosed incopending and commonly assigned U.S. Ser. No. 490,965, filed May 2, 1983and U.S. Ser. No. 500,446, filed June 2, 1983.

The instant invention relates to a new process wherein a large porezeolite in combination with at least one inorganic oxide matrixcomponent is contacted with specific fluoro salts of specific elements,as discussed hereinafter, to provide a zeolite-containing catalyst(s)useful in hydrocarbon conversion processes.

SUMMARY OF THE INVENTION

The above discussion of the prior art is instructive in appreciating therather unusual and novel results observed in the instant invention. Oneof the most striking attributes of the instant invention is theheretofore unknown ability to achieve a catalyst comprising a large porezeolite and inorganic oxide with a Na₂ O content (weight percent) lessthan about 0.3 weight percent, based on the total catalyst weight,without the need of a calcination step to promote removal of Na₂ O or byuse of a commercially unrealistic number of ion exchange steps. Such aprocess has not heretofore been disclosed. In fact, the prior artdiscloses the contrary. For example, U.S. Pat. No. 3,933,983 disclosestreatment of a Y zeolite with solutions of ammonium fluorosilicate andammonium sulfate. At column 12 of U.S. Pat. No. 3,933,983 in Table IV,the treated samples all have a Na₂ O content of greater than 3.35percent by weight (dry basis). Table IV also discloses that it wasnecessary to calcine the zeolites at temperatures of 600° F. prior tothe rare earth exchange to achieve a reduction in the Na₂ O content.Such calcination procedures have been employed heretofore in the priorart to provide for a thermal redistribution of the Na₂ O present in thezeolite.

The instant process relates to the preparation of catalysts by treatmentof a physical mixture of a large pore zeolite and an inorganic matrixwith specific fluoro salts. The catalysts are useful in hydrocarbonconversion processes and in particular in catalytic cracking processes.Although the mechanism by which such novel catalysts are generated isnot entirely understood, it is clear that the interactions of thezeolite, inorganic oxide matrix and the fluoro salt, in a slurry havinga pH greater than 3, are unique in their ability to provide a finalcatalyst having a Na₂ O content less than about 0.3 percent by weight ascharacterized by the fact that such may be achieved without therequirement of a Na₂ O calcination of the catalyst or zeolite containedin the catalyst. Further, it is evident that separate treatment of thezeolite and inorganic oxide matrix with subsequent mixture to form thecatalysts does now result in a catalyst having the same catalyticcharacteristics as the catalysts of the instant invention.

The process of the instant invention employs catalysts prepared bycontacting a mixture of a large pore zeolite and an inorganic oxidematrix with an effective amount of a fluoro salt of the formula:

    A.sub.(n-m) ]MF.sub.n ].sub.z

wherein "A" is an organic or inorganic ionic moiety, e.g., ammonium orquaternary ammonium ions; [MF_(n) ]_(z) is a fluoroanion moietycomprising the element "M"; "M" is an element selected from the group ofelements from Groups VB, VIB, VIIB, VIII, IIIA, IVA and VA of thePeriodic Table of Elements (Sargent-Welch Scientific Company) and rareearth elements; representative of permissible elements, i.e., "M", areboron, aluminum, gallium, silicon, phosphorus, antimony, bismuth,palladium, platinum, iridium, iron, rhenium, molybdenum, tantalum andtitanium; "n" is the coordination number of "M"; "m" is the valence of"M"; and "z" is the valence or charge associated with "A". The fluorosalt is present in an effective amount and may be in the form of anaqueous solution or slurry. The fluoro salt is preferably in an amountof at least 0.0075 moles per 100 grams of the large pore zeolite on ananhydrous basis. The aqueous slurry of the fluoro salt, zeolite andinorganic oxide matrix component(s) has a pH greater than about 3,preferably having a pH within the range of 4 to 7, more preferablybetween about 4 and about 6.5, and is employed at effective conditionsof temperature and time. The catalyst product obtained after thetreatment with the fluoro salt is then preferably treated by ammoniumexchanging the product with ammonium ions, preferably in an amount ofbetween about 1.0 to 10 moles of ammonium ions per 100 grams of thelarge pore zeolite, the weight of zeolite being on an anhydrous basis.The resulting catalysts have a Na₂ O content less than 0.3 percent byweight, preferably less than 0.2 and more preferably less than 0.1,based on the total weight of the catalyst.

The above catalysts may be provided with a catalytically effectiveamount of at least one rare earth cation selected from the groupconsisting of cerium, lanthanum, praseodymium, neodymium, promethium,samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium,lutetium, thulium and ytterbium to provide, preferably, between about0.1 percent by weight and about 20 percent by weight, based on the totalweight of the large pore zeolite employed in the catalyst, of at leastone or more of the aforementioned rare earth cations.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to new catalysts prepared by contacting amixture of a large pore zeolite and an inorganic oxide matrix with aneffective amount of a fluoro salt of the formula:

    A.sub.(n-m) ]MF.sub.n ].sub.z,

wherein "A" is an organic or inorganic ionic moiety, e.g., ammonium andquaternary ammonium ions; [MF_(n) ]_(z) is a fluoroanion moietycomprising the element "M"; "M" is an element selected from the group ofelements from Groups VB, VIB, VIIB, VIII, IIIA, IVA and VA of thePeriodic Table of Elements (Sargent-Welch Scientific Company) and rareearth elements, such as, for example, boron, aluminum, gallium, silicon,phosphorus, antimony, bismuth, palladium, platinum, iridium, iron,rhenium, molybdenum, tantalum and titanium; "n" is the coordinationnumber of "M"; "m" is the valence of "M"; and "z" is the valence orcharge associated with "A". The fluoro salt is employed in an effectiveamount to achieve the desired Na₂ O level and is preferably an amount ofat least 0.0075 moles per 100 grams of the large pore zeolite, on ananhydrous basis. The aqueous slurry of the fluoro salt, large porezeolite and inorganic oxide matrix has a pH greater than 3, preferablyhaving a pH within the range of about 4 to about 7, and more preferablybetween about 4 and about 6.5, and is at effective conditions oftemperature and time. The product is preferably treated by ammoniumexchanging the resultant product of the fluoro salt treatment withammonium ions, preferably in an amount of between about 1 mole to about10 moles of ammonium ions per 100 grams of the large pore zeolite, on ananhydrous basis. The resulting catalysts have a Na₂ O content less than0.3 percent by weight, preferably less than 0.2 and more preferably lessthan 0.1, based on the total weight of the catalyst and such can beachieved without a Na₂ O calcination, as described hereinafter.

Further, the catalysts of this invention may be provided with acatalytically effective amount of at least one rare earth cation and theterm "rare earth cation" is employed to denominate at least one cationselected from the group consisting of cerium, lanthanum, praseodymium,neodymium, promethium, samarium, europium, gadolinium, terbium,dysprosium, holmium, erbium, lutetium, thulium and ytterbium. The rareearth cation is present in an amount between about 0.1 percent by weightand about 20 percent by weight, expressed as the oxide, based on thetotal weight of the zeolite component employed in the catalyst, of atleast one or more of the aforementioned cations. Rare earth cations arepreferably present in an amount between about 1 percent by weight andabout 12 percent by weight and more preferably in an amount betweenabout 2 percent and about 9 percent by weight, based on the total weightof the large pore zeolite.

In this disclosure, including the appended claims, the terms "Na₂ Ocalcination" or characterization of a large pore zeolite or catalyst as"non-calcined" are employed to denominate a thermal treatment of thelarge pore zeolite (alone or in combination with the inorganic oxidematrix) at an effective temperature to effect a thermal redistributionof cations, e.g., alkali metal cations, associated with the zeolite topromote removal of such by ion exchange. The term "Na₂ O calcination",as such applies to Na₂ O removal from a zeolite, is generally understoodby those skilled in the art of zeolites to include treatments attemperatures of 300° C. or greater for about 1 hour, since at such atemperature and for such a period of time at least some redistributionof the cations associated with the zeolite is effected. For example, inthe commercial preparation of catalytic cracking catalysts the zeoliteis calcined at a temperature of 500° C. or greater to redistribute Na₂ Oand facilitate ion-exchange of sodium ions in a post-calcination ionexchange. Processes, such as spray drying, which are carried out attemperatures of about 200° C. for a period of 5 seconds or less are notconsidered to come within the scope of the term "Na₂ O calcination",since such processes are not carried out to remove cations associatedwith the zeolite. Further, a thermal treatment step which is notfollowed by a cation exchange, e.g., ammonium ion or rare earth cationexchange, is not a "Na₂ O calcination" within the meaning of thisinvention, since such has not been carried out to effect the removal ofcations, e.g., sodium or other alkali cations, associated with thezeolite, and as a result facilitate by thermal means an increase in theease of ion exchange of such cations. Although a thermal calcination isnot required to achieve catalysts having low Na₂ O contents, it is clearthat the treatment of mixtures of a large pore zeolite and an inorganicoxide matrix may provide beneficial results when such calcinations arecarried out on the finished catalyst and, accordingly, optionalcalcinations are not excluded from the scope of the instant invention.

The term "large pore zeolite", also generally referred to herein as"zeolite" is employed herein to denominate zeolites having a pore sizegreater than about 6 Angstroms and preferably having an average poresize from about 6 Angstroms to about 15 Angstroms. Representativezeolites include zeolite Y, zeolite X, zeolite beta (U.S. Pat. No.3,308,069), Zeolite ZK-20 (U.S. Pat. No. 3,446,727), LZ-210 (E.P.C.Publication No. 82,211; June 29, 1983, incorporated herein by referencethereto), Zeolite ZSM-3 (U.S. Pat. No. 3,415,736), ZSM-type zeolites,mordenite, zeolite L, zeolite omega, faujasite and mixtures thereof.

The form of the starting large pore zeolite is often that of an alkalimetal aluminosilicate or may be partially in the ammonium form. Thelarge pore zeolite may be provided with ammonium ions by ammoniumexchanging such prior to admixture with the inorganic matrix or themixture may be ammonium or cation exchanged prior to contacting themixture with the fluoro salt solution or slurry. It is preferred tosubject the large pore zeolite to at least a partial ammonium exchangeprior to use in the instant process.

The preferred large pore zeolites are Y-type zeolites, i.e., zeoliteshaving the essential X-ray diffraction pattern of zeolite Y, having aSiO₂ to Al₂ O₃ ratio greater than about 3.5 and preferably greater thanabout 4.5 to about 6. Y zeolites having SiO₂ to Al₂ O₃ ratios greaterthan about 3.5 are disclosed in U.S. Pat. No. 3,130,007. Y zeolites arecommercially available from Union Carbide Corporation under the tradedesignations "Y-52" and "Y-62". "Y-52" and "Y-62" are generallydescribed in Zeolite Catalyst Data Sheets F-3858C (7/79) and F-3480C(7/79) respectively, available from Union Carbide Corporation, Danbury,Conn., incorporated herein by reference. Representative Y-type zeolitesbelieved employable herein include but are not limited to thosedisclosed in U.S. Pat. Nos.: 3,835,032; 3,830,725; 3,293,192; 3,449,070;3,839,539; 3,867,310; 3,929,620; 3,929,621; 3,933,983; 4,058,484;4,085,069; 4,175,059; 4,192,778; 3,676,368; 3,595,611; 3,594,331;3,536,521; 3,293,192; 3,966,643, 3,966,882; and 3,957,623. Theaforementioned patents are merely representative of Y zeolites having aSiO₂ to Al₂ O₃ ratio greater than about 3.5 and are not intended to be acomplete listing of the Y zeolites employable herein. As above noted,the preferred Y zeolites are those having a SiO₂ /Al₂ O₃ ratio betweenabout 4.5 and about 5.5 and desirably have at least a portion of thezeolites' original cations exchanged with ammonium ions, i.e., are atleast partially in the ammonium form. One advantage of the instantprocess is the use of Y zeolites that have not been thermally treated toeffect the thermal rearrangement of the cations of the Y zeolite.Accordingly, Y zeolites such as Y-52 and Y-62 or similarly preparedzeolites are preferred for use in the process of the instant invention.The nature and preparation of such forms of zeolite Y are exemplified bythe aforementioned patents and are well known in the art.

In one embodiment of the instant invention catalytic cracking catalystsare prepared by contacting a mixture of a non-calcined Y zeolite havinga SiO₂ /Al₂ O₃ ratio between about 3.5 and less than 6.0, and aninorganic matrix, wherein the mixture comprises between about 5 andabout 40 weight percent of zeolite Y, between about 10 and about 25weight percent of an acid silica sol and about 45 and about 75 weightpercent of a clay, preferably a kaolin clay, with an aqueous fluoro saltsolution or slurry, to provide mixture of zeolite, matrix and fluorosalt having a pH greater than 3 to about 7, as hereinafter defined, ateffective conditions of concentration, temperature and time. The pH ofthe slurry may be maintained at the appropriate pH by addition of acidicor basic additives, e.g., salts, to provide a slurry in the selected pHrange. In a further embodiment the fluoro salt is selected from thegroup consisting of ammonium hexafluorosilicate and ammoniumhexafluorotitanate and the pH is between about 3 and 7, hereby at leastone of silicon and titanium are inserted as tetrahedral units into thecrystal lattice of the Y zeolite in substitution for aluminum tetrahedrato provide extraneous silicon and/or titanium atoms in the crystallattice.

The term "fluoro salts" as employed herein denominates salts generallycharacterized by the formula:

    A.sub.(n-m) [MF.sub.n ].sub.z

wherein "A" is an organic or inorganic ionic moiety such as ammonium andquaternary ammonium; [MF_(n) ]_(z) is a fluoroanion moiety comprisingthe element "M"; "M" is an element selected from the group of elementsfrom Groups VB, VIB, VIIB, VIII, IIIA, IVA and VA of the Periodic Tableof Elements (Sargent-Welch Scientific Company) and rare earth elements,such as, for example, boron, aluminum, gallium, silicon, phosphorus,antimony, bismuth, palladium, platinum, iridium, iron, rhenium,molybdenum, tantalum and titanium; "n" is the coordination number of"M"; "m" is the valence of "M"; and "z" is the valence or chargeassociated with "A". The fluoroanion "[MF_(n) ]_(z) " may include but isnot limited to BF₄ ⁻, AlF₄ ⁻, PF₆ ⁻, BiF₄ ⁻, AlF₅ ⁻², SiF₆ ⁻², SbF₅ ⁻²,FeF₄ ⁻², PtF₆ ⁻², AlF₆ ⁻³, PdF₇ ⁻³, TaF₈ ⁻³, TiF₆ ⁻² and mixturesthereof.

Fluoro salts in accordance with the above formula include ammoniumtetrafluoroaluminate, ammonium hexafluorophosphate, ammoniumtetrafluorobismuthate, ammonium pentafluoroaluminates, ammoniumhexafluorosilicates, ammonium pentafluoroantimonate, ammoniumtetrafluoroferrite, ammonium hexafluoroplatinate, ammoniumhexafluoroaluminate, ammonium octafluorotantalate, ammoniumheptafluoropalladate, tetramethylammonium tetrafluoroborate, ammoniumtetrafluoroborate and ammonium hexafluorotitanate. In the preferredoperation of the instant invention the fluoro salt is selected as eithera hexafluorosilicate or a hexafluorotitanate, preferably the ammonium orquaternary ammonium salts thereof, as hereinafter discussed in greaterdetail.

Theoretically, there is no lower limit for the concentration of thefluoro salt in the aqueous solution or slurry employed herein in formingthe slurry of the zeolite, fluoro salt and inorganic oxide matrix,provided of course the effective pH of the fluoro salt solution isselected as to avoid undue destructive attack on the zeolite structureand the inorganic oxide matrix. The pH of the slurry containing thefluoro salt, zeolite and inorganic oxide matrix at the processtemperature is greater than 3 and is preferably in the range of 3 to 7,and more preferably between about 4 and about 6.5. Relatively slow ratesof addition of the fluoro salt solution may be beneficial in providingfor adequate time for contacting the fluoro salt and the combined largepore zeolite and inorganic oxide matrix while minimizing possibleconsequent collapse of the crystal structure of the zeolite and/or anydetrimental effect on the inorganic oxide matrix. Practical commercialconsiderations may require that the reaction proceed as rapidly aspossible, and accordingly the effective conditions of reactiontemperature and concentration of fluoro salts may be optimized withrespect to the selected large pore zeolite and inorganic oxide matrix.It is believed that in general the more highly siliceous the large porezeolite, the higher the permissible reaction temperature. Of course, thepresence of the inorganic oxide matrix may serve to both dilute andbuffer the effect of the fluoro salt on the zeolite component. Typicallythe reaction temperature is greater than about 0° C. and is preferablybetween about 10° C. and about 200° C. with the exact temperaturedepending on the selected fluoro salt, solvent, if any, for the fluorosalt and the particular form of the zeolite and inorganic oxide matrixemployed. In most instances the temperature will be greater than 25° C.to about 150° C. and is preferably greater than 50° C. and between about50° C. and 100° C.

The effective concentration of the fluoro salt in the solution or slurrymay be correlated to the temperature, pH at the process temperature andwith the time of contact between the zeolite and inorganic oxide matrixand the fluoro salt solution and with the relative proportions ofzeolite and the inorganic oxide matrix. Fluoro salt solutions havingfluoro salt concentrations of from about 10⁻³ moles per liter ofsolution up to saturation can generally be employed herein, but it ispreferred that concentrations in the range of 0.5 to 1.0 moles of fluorosalt per liter of solution be used. These concentration values are withrespect to true solutions, and are not intended to apply to the totalfluoro salt in slurries of salts in water. Even very slightly solublefluoro salts can be slurried in a solvent, e.g., water, and used as areagent, the undissolved solids being readily available to replacedissolved molecular species consumed in reaction with the zeolite andinorganic oxide matrix. As stated hereinabove, the amount of dissolvedfluoro salts employed with respect to the particular combination oflarge pore zeolite and inorganic oxide matrix being treated will dependto some extent upon the physical and chemical properties of theparticular form of large pore zeolite and the particular inorganic oxidematrix component(s), as well as other process conditions as hereindiscussed in the instant application. The effective amount of fluorosalt to be added is that amount which achieves a final product having aNa₂ O content less than 0.3 percent by weight based on the total weightof the catalyst without the use of a Na₂ O calcination step. Theeffective amount of fluoro salt is preferably greater than 0.0075 molesof fluoro salt per 100 grams of the large pore zeolite, based on theanhydrous weight of the zeolite, and is preferably between about0.01 andabout 0.25. In one embodiment, a Y zeolite is employed and the preferredvalue of fluoro salt is between about 0.05 to about 0.25 moles of fluorosalt per 100 grams of large pore Y zeolite, based on the anhydrousweight of the Y zeolite.

The effective concentration of the ammonium salt in the ammoniumexchange step may be correlated to the temperature and contact timebetween the mixture of the large pore zeolite and inorganic oxide matrixand the ammonium-containing solutions. Ammonium salt solution havingammonium ion concentrations of from 10⁻³ moles per liter of solution upto saturation can generally be employed herein. The effective amount ofammonium ion is preferably in the range of between about 1.0 and about20.0 moles per 100 grams of large pore zeolite, on an anhydrous basis,preferably between about 1.0 and about 10.0 and more preferably betweenabout 1.5 and about 8.0 moles of ammonium per 100 grams of large porezeolite, based on the anhydrous weight. This effective amount ofammonium ion may be provided in a single ion exchange step, but isusually and preferably provided in two or more ion exchange steps. Theammonium salt solutions may be formed from any organic or inorganicspecies that forms ammonium ions on addition to water. Representativesalts are ammonium salts, such ammonium carboxylates (e.g., acetate),nitrate, sulfate, chloride, bromide, fluoride, carbonate and the like.In one embodiment ammonium ions are provided with the fluoro salt toeffect ammonium exchange of the catalyst coincident with the fluoro salttreatment. In this embodiment the ammonium ion concentration is greaterthan that present as a result of any ammonium ion present as a result ofthe fluoro salt.

It is desirable that the integrity of the starting zeolite crystalstructure be maintained throughout the instant process. The rate ofcontacting of the mixture of large pore zeolite and inorganic oxidematrix with the fluoro salt is preferably at a rate such that thestarting zeolite retains in the final catalyst at least 40, preferably60 and more, and more preferably at least 80 percent of its originalcrystallinity.

Techniques for measuring crystallinity of zeolites are well known. Aconvenient technique for assessing the crystallinity of the Y zeoliterelative to the crystallinity of the starting Y zeolite is thecomparison of the relative intensities of the d-spacings of theirrespective X-ray powder diffraction patterns. The sum of the peak areas,in terms of arbitrary units above background, of the starting materialis used as the standard and is compared with the corresponding areas ofthe products. When, for example, the numerical sum of the peak areas ofthe product is 85 percent of the value of the sum of the peak areas ofthe starting zeolite, then 85 percent of the crystallinity has beenretained. In practice it is common to utilize only a portion of thed-spacing peaks for this purpose, as for example, five of the sixstrongest d-spacings. In zeolite Y these d-spacings correspond to theMiller Indices 331, 440, 533, 642 and 555. Other indicia of thecrystallinity retained by the zeolite product are the degree ofretention of surface area and the degree of retention of the adsorptioncapacity. Surface areas can be determined by the well-knownBrunauer-Emmett-Teller method (B-E-T) as described in J. Am. Chem. Soc.,60, 309 (1938) using nitrogen as the adsorbate. In determining theadsorption capacity, the capacity for oxygen at -183° C. at 100 Torr ispreferred.

The essential X-ray powder diffraction patterns may be obtained usingstandard X-ray powder diffraction techniques. The radiation source is ahigh-intensity, copper target, X-ray tube operated at 50 Kv and 40 ma.The diffraction pattern from the copper K-alpha radiation and graphitemonochromator is suitably recorded by an X-ray spectrometerscintillation counter, pulse-height analyzer and strip-chart recorder.Flat compressed powder samples are scanned at 2° (2 theta) per minute,using a 2 second time constant. Interplanar spacings (d) are obtainedfrom the position of the diffraction peaks expressed as 2θ, where θ isthe Bragg angle, as observed on the strip chart. Intensities aredetermined from the heights of diffraction peaks after subtractingbackground.

INORGANIC OXIDE MATRIX COMPONENTS

The catalysts of the present invention are formed from at least onelarge pore zeolite and at least one inorganic oxide matrix component. Asaforementioned, the large pore zeolite and inorganic oxide matrixcomponent(s) are physically combined prior to the treatment with thefluoro salt solution or slurry.

The inorganic oxide matrix may be a porous alumina matrix havingdiscrete particles of various porous aluminas and/or crystallinealuminas. Porous alumina matrices are generally in the form of discreteparticles having total surface areas, as measured by the method ofBrunauer, Emmett and Teller (BET), greater than about 20 square metersper gram (M² /g), preferably greater than about 40 M² /g, and morepreferably, from about 100 M² /g to about 300 M² /g. The pore volume ofsuch alumina matrices will typically be greater than 0.35 cubiccentimeters per gram (cc/g). The average particle size of such aluminaparticles is generallly less than 10 microns and preferably less thanabout 3 microns. The alumina matrix may be preformed and placed in aphysical form such that its surface area and pore structure, if any, arestabilized so that when it is added to an impure, inorganic gelcontaining considerable amounts of residual soluble salts, especiallysodium salts, the salts will not alter the surface and porecharacteristics measurably nor will they promote chemical attack onpreformed porous aluminas. For example, the alumina matrix may be analumina which has been formed by suitable chemical reaction, slurryaged, filtered, dried, washed substantially free of residual salt, e.g.,Na₂ SO₄, and then heated to reduce its volatile content to less thanabout 15 weight percent. The alumina binder may be present with thezeolite and any other inorganic oxide matrix component in an amountranging from about 1 to about 99 weight percent and is often present inan amount from about 5 to about 90 weight percent, based on the totalweight of the finished catalyst. Further, an alumina hydrosol orhydrogel or hydrous alumina slurry may be used initially in thepreparation of the catalyst as precursor of the discrete particles ofalumina in the final catalyst. British Patent Specification No.1,315,533, published May 2, 1983, incorporated herein by reference, isrepresentative of an inorganic matrix formed using an alumina sol.

A wide variety of inorganic oxide matrices may be employed in additionto or in substitution of an alumina matrix. Representatives of suchmatrix systems are disclosed in U.S. Pat. Nos. 3,446,727 and 4,086,187,such U.S. patents being incorporated herein by reference. Accordingly,inorganic oxide matrices which are employable herein include amorphouscatalytic inorganic oxides, such as silica, alumina, silica-alumina,silica-zirconia, silica-magnesia, alumina-boria, alumina-titania and thelike and mixtures thereof. The use of acid silica and acid alumina solsare representative of silicas and aluminas employed in forming suchmatrices. The inorganic oxide gel may be an amorphous silica-aluminacomponent such as a conventional silica-alumina cracking catalyst,several types and compositions of which are commercially available.These materials are generally prepared as a cogel of silica and aluminaor as alumina precipitated on a preformed and preaged hydrogel. U.S.Pat. No. 4,086,187 is representative of an inorganic matrix formed usingan acid silica sol. The silica may be present as a component in thesolids present in said gels in an amount between about 10 and about 99weight percent and often between about 20 and about 90 weight percent.The silica may also be employed in the form of a cogel comprising about75 weight percent silica and about 25 weight percent alumina orcomprising about 87 weight percent silica and about 13 weight percentalumina.

Another method of preparing such catalysts employing silica-alumina andporous alumina is to react sodium silicate with a solution of aluminumsulfate to form a silica/alumina hydrogel slurry which is then aged togive the desired pore properties, filtered to remove a considerableamount of the extraneous and undesired sodium and sulfate ions and thenreslurried in water. The alumina may be prepared by reacting solutionsof sodium aluminate and aluminum sulfate under suitable conditions,aging the slurry to give the desired pore properties of the alumina,filtering, drying, reslurrying in water to remove sodium and sulfateions and drying to reduce volatile matter content to less than 15 weightpercent. The alumina may then be slurried in water and blended in properamounts with a slurry of impure silica-alumina hydrogel. The zeolitecomponent(s) may then be added to this blend. A sufficient amount ofeach component is utilized to give the desired final composition. Theresulting mixture is then filtered to remove a portion of the remainingextraneous soluble salts therefrom. The filtered mixture is then driedto produce dried solids. The dried solids are subsequently reslurried inwater and washed substantially free of the undesired soluble salts. Thecatalyst may then be dried to a residual water content of less thanabout 15 weight percent.

The inorganic oxide matrix component will typically be present in thecatalyst in an amount between about 10 and about 99 weight percent,preferably between about 30 and about 80 weight percent, based on thetotal catalyst. It is also within the scope of the instant invention toemploy other materials with the final cracking catalysts, includingvarious other types of molecular sieves, e.g., aluminophosphates,silicoaluminophosphates and zeolites, clays (such as kaolin clay),carbon monoxide oxidation promoters, etc.

It is anticipated that the catalyst in most instances will includebetween about 5 and about 40 weight percent large pore zeolite and aclay component, preferably a kaolin clay, in an amount between about 30and about 85 percent by weight based on the total weight of thecatalyst. The preferred catalysts will contain between about 10 andabout 25 weight percent of a large pore zeolite, preferably a Y zeolite,and between about 5 percent by weight and about 25 percent by weight ofa silica and/or an alumina component, and between about 45 percent byweight and about 75 percent by weight of a clay, preferably kaolin clay,such weights being based on the total weight of the catalyst.

The finished catalyst, formed of at least one large pore zeolite and atleast one inorganic oxide matrix component, may be formed into the finalform for the catalyst by standard catalyst forming techniques. Suchcatalysts are generally formed by spray drying procedures, suchprocedures being well known in the art. Catalysts may be extrudedthrough a one eighth inch extruder to form pellets and the pellets driedat about 110° C. The extruded pellets may be dried in an air purge at aprogrammed temperature increased from room temperature to about 220° C.over a 1.5 hour period, and may be further then heated to 480° C. over aperiod of 1.5 hour and held at 480° C. for 1.5 hour if desired. Suchpellets may then be crushed and sized to the desired particle size,e.g., less than 150 microns.

The combination of the large pore zeolite and the inorganic oxide matrixmay be exchanged with ammonium and/or other cations before treatmentwith the fluoro salt. Such ion-exchange steps are generally carried outby slurrying the mixture of zeolite and/or inorganic oxide matrix withbetween 5 to 15 volumes of water per the volume of large pore zeoliteand/or inorganic oxide matrix after which a salt of the selected cation,e.g., ammonium or rare earth cations, may be added to the slurry. Theresulting mixture is typically heated to a temperature above about 50°C. for a period between about 0.5 hours and about 3 hours. The mixtureis then filtered and water-washed until excess anion is removed. Theprocess is typically repeated one or more times according to the abovedescribed procedure. Techniques for the ion-exchange of matrixedcatalysts are disclosed in U.S. Pat. No. 3,930,987, incorporated hereinby reference thereto, and such are generally employable herein.

The instant catalysts are well suited for use in all types of catalyticcracking processes. Such processes can be conducted in any conventionalcatalytic cracking manner by employing the cracking catalyst of theinstant invention. The catalysts of this invention are particularlyapplicable to fluid catalytic cracking (FCC) processes. Suitablecatalytic cracking conditions include a temperature ranging from about700° F. to about 1300° F. and a pressure ranging from subatmospheric toabout superatmospheric pressure, typically from about atmospheric toabout 100 psig. The process may be carried out in a fixed bed, movingbed, ebulliating bed, slurry, transferline, riser unit, batchwise orfluidized bed operation. The catalysts of the present invention can beused to convert any of the conventional hydrocarbon feeds used incatalytic cracking, e.g., crude oil-derived feedstocks, that is, it canbe used to crack naphthas, gas oils and residual oils, including havinga high content of metal contaminants. It is especially suited forcracking hydrocarbons boiling in the gas oil range, that is, hydrocarbonoils having an atmospheric pressure boiling point ranging from about450° to about 1100° F. to naphthas to yield not only products having alower boiling point than the initial feed but also products having animproved octane number. Hydrocarbon fractions employable herein includegas oils, residual oils, cycle stocks, whole top crudes and heavyhydrocarbon fractions derived by the destructive hydrogenation of coal,tar pitches, asphalts and the like.

EXAMPLES 1 TO 7

Catalysts were formed by preparing catalyst formulations having thefollowing relative proportions on a weight basis:

    ______________________________________                                        Component       Weight Percent                                                ______________________________________                                        Zeolite Y (Y-52)                                                                              18                                                            SiO.sub.2       20                                                            Kaolin clay     62                                                            ______________________________________                                    

The SiO₂ source was an acid silica sol prepared using an aqueous acidsolution prepared from 9.4 percent mineral acid, buffered to a pH ofabout 3. The mixture was then cooled to room temperature (18° C.-22°C.). This mixture was mixed with a 53 weight percent aqueous solution ofNa₂ SiO₃ by pumping the two solutions through a mixer. The relative flowrates of the two solutions were adjusted to maintain the pH of theproduct at about 2.8 and solid products, if any, were removed as formed.

The catalysts were formed by adding the kaolin clay component to theacid silica sol containing 6.3 percent by weight SiO₂ in water. Themixture was blended for about 10 minutes. The zeolite Y was added tothis mixture with enough water to give a slurry having 25 percent byweight solids. The pH of the mixture was adjusted to less than 4.5(4.3-4.4) by addition of sulfuric acid. The mixture is then mixed for 10minutes. The mixture was then spray dried at 175° C. (contact time lessthan about 5 seconds) and the product sized to exclude particles greaterthan 150 microns. The final catalyst had an average particle size ofabout 64 microns.

The spray dried mixture was then employed to form a catalyst using oneof the following methods.

Method A

The spray dried mixture of zeolite, SiO₂ and kaolin clay is employed toform a catalyst by preparing a slurry of 500 grams of the mixture in 4liters of water at 75° C. The slurry is mixed for 5 minutes andfiltered. The filtered solid is reslurried in 4 liters of a (NH₄)₂ SO₄solution at 75° C. where the solution is prepared by dissolving 200grams of (NH₄)SO₄ in 4 liters of distilled water. The slurry was mixedfor 30 minutes. A 10% by weight solution of ammonium hexafluorosilicatesolution was added to the slurry by adding 168 milliliters dropwise overa period of one hour. The mixture was then cooled to 50° C. To thismixture there was added 54.2 grams of Al₂ (SO₄)₃. The resulting mixturewas mixed for two hours, filtered, the solid product washed with 2liters of distilled water at 50° C. and filtered, and then the solidproduct was slurried at 50° C. in 4 liters of an (NH₄)₂ SO₄ solution(160 grams of (NH₄)₂ SO₄ in 4 liters of H₂ O), mixed for 10 minutes andfiltered. The solid product was then washed with 4 liters of distilledwater at 50° C. and filtered. The previous step is repeated twoadditional times except that instead of washing the solid product with 4liters of distilled water the product is washed with 10 liters of waterat 50° C. which has had the pH adjusted to 9.0 by addition of NH₄ OH.The wash liquid is tested for sulfate anions and washing continued untilsulfate was not qualitatively detected (less than about 500 ppm). Thefinal solid product was either air dried for 10 to 24 hours or was driedovernight (6 hours to 12 hours) at 100° C. in air.

Method B

Method B is similar to Method A except that the mixture of zeolite Y,silica and kaolin clay was treated with an aqueous (NH₄)₂ SO₄ solutionafter the slurry was filtered and before reslurry of the filtered solidwith the 4 liters of (NH₄)₂ SO₄ solution. This (NH₄)₂ SO₄ treatment stepwas carried out similar to the final (NH₄)₂ SO₄ treatment steps employedin Method A. Further, the final treatment step of Method A involving(NH₄)₂ SO₄ was carried out only twice instead of the three times ofMethod A.

The catalyst prepared in example 1 was analyzed for Na₂ O, SiO₂ and Al₂O₃. In addition, spray dried samples were analyzed of: (1) a mixture ofzeolite Y (sodium form), the kaolin clay and the SiO₂, as employed inexamples 1 to 19; and (2) of the kaolin clay and SiO₂. The chemicalanalyses were as follows:

    ______________________________________                                        Sample      Na.sub.2 O                                                                            SiO.sub.2 Al.sub.2 O.sub.3                                                                    Na.sub.2 O*                               ______________________________________                                        Example 1   0.1      66.34    30.1  --                                        NaY         8.4     57.2       28.11                                                                              6.98                                      Kaolin Clay 5.9     55.9      31.6  5.9                                       ______________________________________                                         *Percent of reported Na.sub.2 O present as Na.sub.2 SO.sub.4?            

The catalysts of examples 1 to 7 were evaluated by microactivity tests(MAT) according to ASTM test method D-3907 employing a feedstock havingan API gravity of 24.0°, an IBP (Initial Boiling Point) of 354° F., aFBP (Final Boiling Point) of 1077° F. and a UOP K Factor of 11.8. TheUOP K Factor is defined as ##EQU1## where "T_(B) " is the averageboiling point in degrees Rankine and "d" is the specific gravity 60°/60°F. The percent coke, selectivity to gasoline products and percentconversion are set forth in Table I. Gasoline products are hydrocarbonproducts containing C₅ hydrocarbons (boiling at about 110° F.) tohydrocarbons boiling at or below 430° F. Coke refers to hydrocarbonswhich are adsorbed by the catalysts and are not removed by stripping.

                                      TABLE I                                     __________________________________________________________________________         Steaming                       % Gasoline                                                                          Percent                             Example                                                                            Temperature (°F.).sup.1                                                          Method                                                                             Rare Earth.sup.2                                                                     Na.sub.2 O.sup.2                                                                  % Coke.sup.3                                                                       Selectivity.sup.3                                                                   Conversion.sup.3                    __________________________________________________________________________    1    1450      B    0      0.14                                                                              0.51 79.2  49.5                                2    1450      A    0.75   0.21                                                                              0.57 79.2  59.4                                3    1450      B    0.75   0.13                                                                              0.88 77.6  59.3                                4    1450      A    2.7    0.21                                                                              0.82 79.2  57.9                                5    1450      B    1.95   0.13                                                                              0.73 76.3  62.5                                6    1500      A    0      0.23                                                                              0.62 77.0  57.8                                7    1450      A    0.5    0.21                                                                              0.47 77.2  55.9                                __________________________________________________________________________     .sup.1 All catalysts were steamed prior to testing by employing 100% stea     (weight basis) for 2 hours.                                                   .sup.2 Weight percent based on total catalyst weight.                         .sup.3 % Conversion is defined in ASTM test method D3907. % Gasoline          Selectivity is the (weight of gasoline product/weight of                      feedstock)/(Percent Conversion). % Coke is the (weight of coke)/(weight o     feedstock).                                                              

EXAMPLE 8

A catalyst was prepared according to Method B as above described, toshow that a catalyst treated only with an equivalent molar amount ofammonium solution, as obtained by use of the ammonium fluoro saltsolutions and ammonium solutions employed in Examples 1-7, does notprovide a catalyst having a final Na₂ O content less than 0.3 percent byweight, based on the total catalyst weight. The catalyst was preparedaccording to Method B by substituting a solution of ammonium sulfatecontaining an equivalent molar amount of ammonium ion for the ammoniumhexafluorosilicate and aluminum sulfate solution employed in Method B.The final catalyst contained 0.412 weight percent Na₂ O and zero weightpercent rare earth, expressed as the oxide.

These results demonstrate the importance of preparing the catalystaccording to this invention by treatment of the large pore zeolite andinorganic oxide matrix with a fluoro salt and not simply withammonium-containing solutions.

EXAMPLES 9 TO 11

Three catalysts were prepared as in examples 1 to 7, according to MethodB, except that 10%, 30% and 40% by weight of the zeolite Y component,respectively, in examples 9, 10 and 11, was employed instead of the 18percent by weight employed in examples 1 to 7. A portion of the claycomponent was added or removed to compensate for the change in theweight percent of the zeolite component. The catalysts were not treatedwith rare earth cations.

The three catalysts were steam deactivated in 100% steam (volume basis)for 2 hours at the temperatures set forth in Table II and when twotemperatures were employed such were denominated as Runs A or B. Thecatalysts were evaluated according to the procedure employed forexamples 1 to 7 and the following results obtained, as shown in TableII:

                  TABLE II                                                        ______________________________________                                                                          % Gasoline                                                                            %                                                 Temp          %     Selec-  Conver-                             Example                                                                              Run    (°F.)                                                                          Na.sub.2 O                                                                          Coke* tivity* sion*                               ______________________________________                                         9     A      1450    0.16  0.59  70.9    44.5                                10     A      1450    0.25  0.95  71.9    63.5                                10     B      1550    0.25  0.40  80.3    44.2                                11     A      1450    0.15  1.12  74.3    70.7                                11     B      1550    0.15  0.56  72.7    56.0                                ______________________________________                                         *As defined in Table I                                                   

EXAMPLE 12

A catalyst was prepared according to Method B except that the 18 weightpercent Y-52 was replaced by 18 weight percent LZ-210 (silica-to-aluminaratio of 6.5) containing 2.5 weight percent Na₂ O based on the weight ofLZ-210 and zero percent by weight rare earth. The catalyst was treatedat 1450° F. in 100 percent steam for 2 hours and evaluated by theprocedure employed for examples 1 to 7. The results of the evaluationand of the % Gasoline Selectivity and % Coke were as follows:

% Conversion: 53.1

% Gasoline Selectivity: 73.5

% Coke: 0.82

EXAMPLE 13

A catalyst was prepared according to Method B, except that the pH of thecatalyst slurry was maintained at pH 7 by continuous addition of 20weight percent aqueous NH₄ OH during the addition of the fluoro salt.The catalyst contained 0.39 percent by weight Na₂ O, based on the weightof the finished catalyst. The catalyst was treated in 100% steam for 2hours at 1450° F.

The catalyst was evaluated according to ASTM test method D-3907 asdescribed for examples 1 to 7 and the % Conversion and % GasolineSelectivity were as follows:

% Conversion: 59.9

% Gasoline Selectivity: 74.6

EXAMPLE 14

A catalyst was prepared as in examples 1 to 7, according to Method B,except the addition of aluminum sulfate was omitted. Two portions of thecatalyst were treated in 100% steam for 2 hours at 1450° F. and 1550°F., respectively. The catalyst was evaluated according to ASTM testmethod D-3907 as described for examples 1 to 7 and gave the followingresults:

    ______________________________________                                                         Catalyst                                                     Deactivation Temp. (°F.)                                                                  1450° F.                                                                        1550° F.                                   ______________________________________                                        % Conversion       42.5     39.5                                              % Gasoline Selectivity                                                                           78.3     82.3                                              % Coke             0.43     0.39                                              % Na.sub.2 O*      0.13     0.13                                              % RE.sub.2 O.sub.3 *                                                                             0        0                                                 ______________________________________                                         *based on total catalyst weight                                          

EXAMPLE 15

A catalyst was prepared as in examples 1-7 according to Method B exceptthat the ammonium fluorosilicate was replaced by (NH₄)₂ TiF₆. The amountof (NH₄)₂ TiF₆ employed was that amount required to furnish sufficienttitanium to substitute 27.5% of the framework aluminum atoms if 100percent substitution of TiO₂ tetrahedra for AlO₂ tetrahedra occurred.The catalyst was not rare earth exchanged. Chemical analysis of theproduct gave the following:

    ______________________________________                                                  Weight Percent                                                      ______________________________________                                        SiO.sub.2   63.4                                                              Al.sub.2 O.sub.3                                                                          30.11                                                             Na.sub.2 O  0.22                                                              TiO.sub.2   3.55                                                              ______________________________________                                    

The catalyst was steam (100%) deactivated at 1450° F. for 2 hours andevaluated according to the procedure employed for examples 1 to 7. Theresults were as follows:

% Conversion: 59.2

% Gasoline Selectivity: 75.7

EXAMPLE 16

A catalyst was prepared as in example 12, except that the solution ofammonium hexafluorosilicate and aluminum sulfate was replaced as wasdone in example 8. Six portions of the catalyst (Runs A to F) wereevaluated by rare earth exchanging the samples to a given rare earthcontent and by treatment of the catalysts in 100% steam for 2 hours at1450° F., 1500° F. or 1550° F. The catalysts were evaluated according tothe procedure employed for examples 1 to 7 and gave the followingresults as shown in Table III:

                  TABLE III                                                       ______________________________________                                                                          %                                                Temp    %       %      %     Gasoline.sup.2                                                                        % Con-                              Run  (°F.)                                                                          Na.sub.2 O.sup.1                                                                      RE.sub.2 O.sub.3.sup.1                                                               Coke.sup.2                                                                          Selectivity                                                                           version.sup.2                       ______________________________________                                        A    1450    0.47    0.75   0.7   75.6    63.7                                B    1500    0.47    0.75   0.4   80.5    47.2                                C    1550    0.47    0.75   0.2   58.3     6.9                                D    1450    0.47    2.5    0.94  71.1    56.6                                E    1500    0.47    2.5    0.58  73.4    47.5                                F    1500    0.47    2.5    0.19  72.1    14.2                                ______________________________________                                         .sup.1 based on total weight of the catalyst                                  .sup.2 As defined in Table I.                                            

What is claimed is:
 1. A process for preparing a catalyst comprising thefollowing steps:(i) contacting a mixture of a large pore zeolite and aninorganic oxide matrix, with a fluoro salt of the formula

    A.sub.(n-m) [MF.sub.n ].sub.z                              ( 1)

wherein "A" is an organic or inorganic ionic moiety; [MF_(n) ]_(z) is afluoroanion moiety comprising the element "M"; "M" is an elementselected from the group of elements from Groups VB, VIB, VIIB, VIII,IIIA, IVA and VA of the Periodic Table of Elements; "n" is thecoordination number of "M"; "m" is the valence of "M"; and "z" is thevalence or charge associated with "A"; at a pH greater than about 3, ateffective conditions of temperature and time.
 2. The process accordingto claim 1 comprising the additional steps of ammonium exchanging theproduct to provide a catalyst having a Na₂ O content less than 0.3percent by weight, based on the total catalyst weight.
 3. The process ofclaim 1 or 2 wherein the product is cation exchanged with acatalytically effective amount of at least one rare earth cationselected from the class consisting of cerium, lanthanum, praseodymium,neodymium, promethium, samarium, europium, gadolinium, terbium,lutetium, dysprosium, holmium, erbium, thulium and ytterbium.
 4. Theprocess of claim 1 wherein said large pore zeolite is a Y zeolite havinga SiO₂ /Al₂ O₃ ratio greater than about 3.5.
 5. The process according toclaim 4 wherein said Y zeolite has a SiO₂ /Al₂ O₃ ratio between about4.0 and about 6.5.
 6. The process according to claim 4 wherein said Yzeolite is at least partially in the ammonium cationic form.
 7. Theprocess of claim 1 wherein the effective pH is between 3 and about
 7. 8.The process of claim 7 wherein the pH is between about 4.0 and about6.5.
 9. The process of claim 1 wherein the effective temperature is atleast 50° C.
 10. The process of claim 9 wherein the effectivetemperature is between about 50° C. and about 100° C.
 11. The process ofclaim 1 wherein the effective time is between about 0.1 hours and about2 hours.
 12. The process of claim 11 wherein the effective time isbetween about 0.2 hour and about 1 hours.
 13. The process of claim 1wherein the fluoro salt is provided in an amount greater than 0.0075moles per 100 grams of large pore zeolite.
 14. The process of claim 13wherein the fluoro salt is provided in an amount between about 0.05 andabout 0.2 moles per 100 grams of large pore zeolite.
 15. The process ofclaim 2 wherein the catalyst contains less than 0.2 percent by weightNa₂ O, based on the total weight of the catalyst.
 16. The process ofclaim 15 wherein the catalyst contains less than 0.1 percent by weightNa₂ O based on the total weight of the catalyst.
 17. The process ofclaim 1 wherein the inorganic oxide matrix is selected from the groupconsisting of silicas, aluminas, silica-aluminas, clays and mixturesthereof.
 18. The process of claim 17 wherein the zeolite and inorganicoxide matrix comprise a mixture of between about 5 and about 40 percentby weight of the large pore zeolite, 10 percent and about 25 percent byweight of at least one of silica and alumina and between about 45percent and about 75 percent of a clay.
 19. The process of claim 18wherein the zeolite and inorganic oxide matrix comprise a mixture ofbetween about 10 and about 25 percent by weight zeolite, between about10 percent and about 25 percent by weight of at least one of silica andalumina and between about 45 percent and about 75 percent of a kaolinclay.
 20. The process of claim 18 wherein the zeolite is zeolite Y, thesilica is an acid silica sol and the clay is kaolin clay.
 21. Theprocess of claim 18 wherein the alumina is an acid alumina sol.
 22. Theprocess of claim 19 wherein the zeolite is present in an amount ofbetween about 15 and about 20 percent by weight, based on the totalweight of the catalyst.
 23. The process of claim 18 wherein the finalproduct contains less than 0.2 percent by weight Na₂ O, based on thetotal weight of the catalyst, and between about 1 and about 20 weightpercent of at least one rare earth cation, based on the weight ofzeolite.
 24. The process of claim 1 wherein at least 40 percent of thecrystallinity of the starting large pore zeolite is retained by thezeolite in the catalyst.
 25. The process of claim 1 wherein said largepore zeolite is selected from the group consisting of zeolite Y, zeoliteX, zeolite beta, Zeolite ZK-20, zeolite LZ-210, Zeolite ZSM-3 andmixtures thereof.
 26. The process of claim 25 wherein said zeolite is amixture of a Y zeolite and LZ-210.
 27. The process of claim 25 whereinsaid zeolite is Zeolite beta.
 28. The process of claim 26 wherein saidzeolite is Zeolite ZK-20.
 29. The process of claim 25 wherein saidzeolite is ZSM-3.
 30. The process of claim 25 wherein said zeolite isLZ-210.
 31. The process of claim 1 wherein "M" is selected from thegroup consisting of silicon, phosphorus, antimony, bismuth, palladium,platinum, iridium, iron, rhenium, molybdenum, tantalum, titanium andmixtures thereof.
 32. The process of claim 31 wherein "M" is selectedfrom the group consisting of silicon, titanium and mixtures thereof. 33.The process of claim 1 wherein "A" is selected from the group consistingof cations of ammonium, quaternary ammonium and mixtures thereof. 34.The process of claim 33 wherein the fluoro salt is ammoniumhexafluorosilicate.
 35. The process according to claim 1 for thepreparation of a catalyst wherein the catalysts are prepared by:(i)contacting a mixture of Y zeolite having a SiO₂ /Al₂ O₃ ratio of betweenabout 3.5 and about 6, and an inorganic oxide matrix, said matrixcomprising a mixture of a kaolin clay and at least one of silicas,aluminas, silica-aluminas, with a fluoro salt selected from the groupconsisting of ammonium hexafluorosilicate, ammonium hexafluorotitanateand mixtures thereof in an amount of at least 0.0075 moles per 100 gramsof zeolite, at a pH value within the range of 3 to about 7 at effectiveconditions of temperature and time whereby at least one of silicon andtitanium is inserted as tetrahedral units into the crystal lattice ofthe zeolite in substitution for aluminum tetrahedra; and (ii) ammoniumexchanging the product of step (i) to provide a catalyst having a Na₂ Ocontent less than 0.3 percent by weight based on the total catalystweight.
 36. The process according to claim 35 wherein said catalyst isprepared in the absence of a Na₂ O calcination.
 37. The process of claim35 wherein said zeolite is zeolite Y having a SiO₂ to Al₂ O₃ ratiobetween about 4.5 and 6.0, said fluoro salt is ammoniumhexafluorosilicate and said temperature is greater than 50° C.
 38. Theprocess according to claim 35 wherein the product of step (ii) isprovided with a catalytically effective amount of at least one rareearth cation selected from the class consisting of cerium, lanthanum,praseodymium, neodymium, promethium, samarium, europium, lutetium,gadolinium, terbium, dysprosium, holmium, erbium, thulium and ytterbiumto provide between about 1 to about 20 weight percent of at least onerare earth cation, based on the weight of the zeolite.
 39. The processof claim 35 wherein said zeolite is Y zeolite having a SiO₂ /Al₂ O₃ratio between about 4.5 and about 6 and being at least partially in theammonium cationic form.
 40. The process of claim 35 wherein theeffective pH is between about 4.0 and about 6.5.
 41. The process ofclaim 1 wherein the effective temperature is at least 50° C.
 42. Theprocess of claim 41 wherein the effective temperature is between about75° C. and about 150° C.
 43. The process of claim 41 wherein theeffective time is between about 0.1 hours and about 2 hours.
 44. Theprocess of claim 35 wherein the fluoro salt is provided in an amountbetween about 0.05 and about 0.2 moles per 100 grams of large porezeolite.
 45. The process of claim 35 wherein the catalyst contains lessthan 0.2 percent by weight Na₂ O, based on the total weight of thecatalyst.
 46. The process of claim 45 wherein the catalyst contains lessthan 0.1 percent by weight Na₂ O based on the total weight of thecatalyst.
 47. The process of claim 35 wherein the inorganic oxide matrixis selected from the group consisting of silicas, aluminas,silica-aluminas, clays and mixtures thereof.
 48. The process of claim 47wherein the zeolite and inorganic oxide matrix comprise a mixture ofbetween about 5 and about 40 percent by weight of the large porezeolite, 10 percent and about 25 percent by weight of at least one ofsilica and alumina and between about 45 percent and about 75 percent ofa clay.
 49. The process of claim 48 wherein the zeolite and inorganicoxide matrix comprise a mixture of between about 10 and about 25 percentby weight zeolite, between about 10 percent and about 25 percent byweight of at least one of silica and alumina and between about 45percent and about 75 percent of a kaolin clay.
 50. The process of claim48 wherein the zeolite is zeolite Y, the silica is an acid silica soland the clay is a kaolin clay.
 51. The process of claim 50 wherein thealumina is an acid alumina sol.
 52. The process of claim 35 wherein thezeolite is present in an amount of between about 15 and about 20 percentby weight, based on the total weight of the catalyst.
 53. The process ofclaim 48 wherein the final product contains less than 0.2 percent byweight Na₂ O, based on the total weight of the catalyst, and betweenabout 0.1 and about 10 weight percent of at least one rare earth cation.54. A process for preparing a catalyst comprising the followingsteps:(i) contacting a mixture of a Y zeolite having a SiO₂ /Al₂ O₃ratio between about 3.5 and 6 and an inorganic oxide matrix, with afluoro salt of the formula

    A.sub.(n-m) [MF.sub.n ].sub.z                              ( 1)

wherein "A" is an organic or inorganic ionic moiety; [MF_(n) ]_(z) is afluoroanion moiety comprising the element "M"; "M" is an elementselected from the group of elements from Groups VB, VIB, VIIB, VIII,IIIA, IVA and VA of the Periodic Table of Elements; "n" is thecoordination number of "M"; "m" is the valence of "M"; and "z" is thevalence or charge associated with "A"; at a pH from 3 to about 7 in anamount of at least 0.0075 moles per 100 grams of the large pore zeoliteon an anhydrous basis; (ii) ammonium exchanging the product of step (i)to provide a catalyst having a Na₂ O content less than 0.3 percent byweight, based on the total catalyst weight; and (iii) with the provisothat such process is carried out in the absence of a Na₂ O calcinationof said Y zeolite.
 55. The cracking catalyst prepared by the process ofclaim
 1. 56. The cracking catalyst prepared by the process of claim 2.57. The cracking catalyst prepared by the process of claim
 3. 58. Thecracking catalyst prepared by the process of claim
 18. 59. The crackingcatalyst prepared by the process of claim
 35. 60. The cracking ofcatalyst prepared by the process of claim
 54. 61. The process forpreparing catalysts consisting essentially of the steps of:(i)contacting a fluoro salt with a mixture of a large pore zeolite selectedfrom the class consisting of zeolite Y, zeolite X, zeolite beta, zeoliteLZ-210, zeolite ZK-20, zeolite ZSM-3 and mixtures thereof and aninorganic oxide matrix selected from the group consisting of aluminas,silicas, silica-aluminas, clays, and mixtures thereof, wherein thefluoro salt is of the formula

    A.sub.(n-m) [MF.sub.n ].sub.z                              ( 1)

wherein "A" is an organic or inorganic ionic moiety; [MF_(n) ]_(z) is afluoroanion of element "M"; "M" is at least one of boron, aluminum,gallium, silicon, phosphorus, antimony, bismuth, palladium, platinum,iridium, iron, rhenium, molybdenum, tantalum and titanium; "n" is thecoordination number of "M"; "m" is the valence of "M"; and "z" is thevalence or charge associated with "A"; at a pH greater than 3 for aneffective time at an effective temperature; (ii) ammonium exchanging theproduct of step (i); (iii) rare earth exchanging the product of step(ii); (iv) obtaining without Na₂ O calcination a product containing lessthan 0.3 weight percent Na₂ O, based on the weight of the catalyst, andbetween about 1 and about 20 weight percent of at least one rare earthelement cation selected from the group consisting of cerium, lanthanum,praseodymium, neodymium, promethium, samarium, europium, lutetium,gadolinium, terbium, dysprosium, holmium, erbium, thulium and ytterbium.62. The process of claim 61 wherein the large pore zeolite is zeolite Yand the fluoro salt is selected from the group consisting offluorosilicates, fluorotitanates and mixtures thereof.
 63. The processof claim 61 wherein at least one of silicon and titanium is inserted asa tetrahedral unit into the crystal lattice of the large pore zeolite insubstitution for aluminum tetrahedra.
 64. The process of claim 1 whereinsaid process is carried put in the presence of an aluminum salt.
 65. Theprocess of claim 1 wherein said process is carried out in the presenceof aluminum sulfate.
 66. The process of claim 35 wherein said process iscarried out in the presence of an aluminum salt.
 67. The process ofclaim 66 wherein said aluminum salt is aluminum sulfate.
 68. The processof claim 37 wherein said process is carried out in the presence of analuminum salt.
 69. The process of claim 68 wherein said aluminum salt isaluminum sulfate.
 70. The process of claim 54 wherein said process iscarried out in the presence of an aluminum salt.
 71. The process ofclaim 70 wherein said aluminum salt is aluminum sulfate.
 72. The processof claim 61 wherein said process is carried out in the presence of analuminum salt.
 73. The process of claim 72 wherein said aluminum salt isaluminum sulfate.